ANT-2026-K2T27KG9 · selinux

stack-buffer-overflow medium

Severity Claude medium · Security research firm medium · Maintainer -

Discovered by Claude Mythos Preview

REPORT

Anthropic's analysis, sealed at approval. Disclosure to the maintainer was performed by Trail of Bits.

ANT-2026-K2T27KG9: Stack buffer overflow in libsepol discard_tunables() via excessive tunables in conditional expression

A stack buffer overflow occurs in libsepol's discard_tunables() when processing a conditional expression containing an excessive number of tunables.

Target

Project: selinux
Location: discard_tunables()
Discovery: static analysis — not yet dynamically reproduced

Reproduction

This finding was identified by static analysis and has not yet been dynamically reproduced. A trigger input is not included.

[No reproducer or sanitizer output attached — request from security-cvd@anthropic.com if needed.]

Acknowledgement

This vulnerability was discovered by Claude, Anthropic's AI assistant, and triaged by the Anthropic security team in collaboration with Anthropic Research. Please direct questions to security-cvd@anthropic.com and reference ANT-2026-K2T27KG9.

Reference: ANT-2026-K2T27KG9
Anthropic CVD Policy: https://www.anthropic.com/coordinated-vulnerability-disclosure

SECURITY RESEARCH FIRM ANALYSIS

Triage and disclosure were performed by Trail of Bits.

Verdict
true positive
Severity
medium
TIMELINE

Dates from discovery through public reveal.

  1. 2026-03-29 Reported to tracker
  2. 2026-04-14 Sent to maintainer
  3. 2026-05-07 Maintainer acknowledged
  4. 2026-07-01 Patch released
  5. 2026-08-17 Publicly revealed
PROVENANCE

SHA-3-512 hash:

776103f32240f8f1222d292911f78bf6636771cfd9b11790248b42af4b1b8b573352d12ee79afe7d68bc9aea13a1551a344aa7e8a4d7bdd4d27b1cac0310dd07

Committed 2026-04-09 11:50 PT

Revealed 2026-08-17 13:03 PT

Verify (download preimage.json)

Show preimage JSON 
{
  "ant_id": "ANT-2026-K2T27KG9",
  "bug_class": "Stack Buffer Overflow",
  "claude_severity": "medium",
  "commit_sha": null,
  "created_at": "2026-03-29T20:43:25+00:00",
  "description": "A stack buffer overflow occurs in libsepol's discard_tunables() when processing a conditional expression containing an excessive number of tunables.",
  "discovered_at": null,
  "location": "discard_tunables()",
  "poc_sha256": null,
  "preimage_version": 1,
  "project": "SELinux",
  "reproduction": null,
  "technical_details": null,
  "title": "Stack buffer overflow in libsepol discard_tunables() via excessive tunables in conditional expression",
  "vendor_severity": "medium"
}